Study Type--Therapy (case series) Level of Evidence 4. What's known on the subject? and What does the study add? Supine percutaneous nephrolithotomy (PCNL) has been described for over a decade and has equivalent success rates when compared with the more widely used prone position. The supine position offers a shorter operative duration with better access to the airway for the anaesthetist and also allows for simultaneous retrograde intra-renal surgery (RIRS). Various supine positions have been described but there is little data regarding their differing benefits and disadvantages. The present study looks at the different supine PCNL positions and compares the strengths and weaknesses of each. Each of the previously described supine PCNL positions have some limitations, e.g. ease of puncture under image guidance, the ability and ease of making and dilating multiple tracts, and allowing simultaneous RIRS. The new 'Barts flank-free modified supine position' is described, which seems to offer a good compromise and addresses some of these issues. It is important to highlight that one supine position does not fit all and the endourologist should familiarise themselves with these positions so the appropriate position can be used for the right patient and stone burden. OBJECTIVE • To discuss the relative merits of the different described supine positions for percutaneous nephrolithotomy (PCNL) and highlight the new 'Barts flank-free modified supine position', as the last decade has seen the emergence of various supine positions for PCNL. METHODS • We reviewed English publications on supine PCNL to look at the different positions being used to carry out PCNL and their relative merits. • We describe the new 'Barts flank-free modified supine position', which we think will add significantly to the armamentarium of the endourologist. RESULTS • Five different supine positions are discussed. • These include the complete supine, the Valdivia, the Galdakao modified Valdivia, the Barts modified Valdivia and the herein described Barts flank-free modified supine position • These positions all differ in regard to ease of puncture under image guidance, operative field availability, ability to make multiple tracts and the ease of combining retrograde intra-renal surgery. CONCLUSIONS • All of the supine positions decrease operative duration, as there is no need for repositioning and allow quick access to the airway for the anaesthetist. • However, one supine position does not fit all and the right one must be chosen for the right patient with the right stone burden. It is important for endourologists of today to familiarise themselves with these positions to be able to make these judgements.